#' @title Difference in Differences
#' @description Difference in Differences with multiple periods and variation in
#'  treatment timing
#'
#' @docType package
#' @name did
#' @import stats
#' @import BMisc
#' @import MASS
#' @import pbapply
#' @import knitr
#' @import ggplot2
#' @import utils
#' @import gridExtra
#' @import DRDID
#' @import plm
NULL
